Almost half the injuries in ballet are to the foot and occur when ballerinas dance on the tip of their toes, that is a "full-pointe". Fatigue of muscles crossing the metatarsal-phalangeal (m-p) joints is thought to be a causal factor. Tendonitis of flexor hallucis longus, acute intrinsic muscle spasm and repetitive muscle strain injuries at midtarsal are common in ballerinas and occur when manoeuvring to the full-pointe position. Fatigue is also thought to be a major factor in fractures to the phalanges, metatarsals and sesamoid bones as acute fractures usually occur towards the end of a day when the feet of the dancer are very tired.
The pointe shoes themselves do offer some support but quickly breakdown and lose their beneficial characteristics, often ready to be discarded after one performance. Ballet shoes have not kept pace with the technical demands of ballet choreography. The relative contribution of the ankle plantarflexor muscles and m-p flexor group to the energetics of rising onto full-pointe is approximately 60% for the ankle joint and 40% for the m-p joints. The relatively small m-p muscles, therefore, must generate almost half the total energy required.